Backplanes provide both a physical support for and circuitry to electrically interconnect a number of daughter cards having electronic components mounted thereon. Of the several ways of mounting daughter cards on a backplane, a two-piece, multiple-contact connector system offers advantages not otherwise available. One such system is made and sold by AMP Incorporated of Harrisburg, PA, under the Trademark "AMP HDI Two Piece PC Board Connector".
One connector, the "pin header", is plugged into or otherwise attached to the backplane and the mating second connector, the "receptacle", is plugged into or otherwise attached to the daughter card. When the two connectors are removably joined or mated, circuits on the backplane and daughter card are electrically connected through the engaging contacts in the joined connectors.
As disclosed in U.S. Pat. No. 4,655,518, a two-piece connector was modified by providing grounding contacts along the plastic sidewalls of the respective connectors. The contacts in the pin header are positioned in recesses in an inside surface of a sidewall with the contact portion thereof; i.e., a convex-shaped, single resilient beam, facing inwardly towards the signal pins positioned between the sidewalls. The ground contacts in the receptacle were placed along the outside surface of a sidewall so that they would slidingly engage the resilient beams in the pin header when the connectors were joined. The normal force between the engaged ground contacts is obtained by the beam being pushed against the sidewall.
As is well known, plastic under compression tends to soften in warm environments and the sidewall loses some of its ability to support the beams adequate. Thus, the normal force drops off, reducing the ability of the engaging contacts to transmit electrical current therethrough. Accordingly, it is now proposed to provide a connector system, of the type described above, wherein the normal forces between all the contacts are achieved from the structure of the contacts themselves and do not rely on the plastic sidewalls.